Hydraulic diaphragm brake



Jan. 29, 1935.

,J. A. DE vn'o Re. 19,443

HYDRAULIC DIAPHRAGM BRAKE Original Filed Aug. 17, 1926 2 Sheets-Sheet 1INVENTOR. J hn 6?. De Vno BY ATTORNEY Jan. 29, 1935. J. A. DE VITOHYDRAULIC DIAPHRAGM BRAKE 2 Sheets-Sheet 2 Original Filed Aug. 1'7, 1926INVENTOR.

John (4. Be Vno 5? BY MTORNEY Reiuued Jan. 29, 1935 UNITED STATES PATENTOFFICE -Bendix Brake Company, South corporation of Illinois Bend, Ind &

Original No. 1,791,717, dated February 10, 1931, Serial No. 129,691,August 17, 1926. Application for reissue January 28, 1933, Serial No.654,080

5 Claims. (Cl. 60-545) My invention is a hydraulic diaphragm brake orother hydraulic structure in which 8. diaphragm is utilized in thetransmission of hydraulic power or force.

One of the difllculties of hydraulic mechanism such as brakes'is in theleakage of the compression fluid around the pistons or piston packingbore in the compressor or pump and in the device for applying thepressure through moving pistons. In the application of hydraulic brakesthe movement of a piston in the compressor is comparatively small, andthe movement of the pistons in the brake mechanism for applying thispower to the brakes is also small, but nevertheless there is suflicientleakage to be inconvenient and to require replenishing.

My invention applies both to compressors or pumps and also to the meansfor utilizing a compressed fluid in which the movement is comparativelysmall and hence I use a resilient flexible diaphragm which may giveunder pressure and thus prevent direct engagement'of the fluid with thepistons both in the compressors or pumps and in the cylinders utilizingpistons to deliver power.

An object of my invention therefore is in the construction ofcompressors or pumps having a restricted motion and in power delivery ortransmitting devices having cylinders with pistons to utilize resilientdiaphragms, such as rubber diaphragms through which the pressure istransmitted to or from the hydraulic fluid on one side of the diaphragm,the piston being on the other side of the diaphragm.

A specific use of my invention is its application to hydraulic brakes asapplied to automobiles in which I utilize the diaphragm in thecompressor or pump and also in the cylinders for applying the power tothe brake mechanism.

In constructing my invention, I provide compressors or pumps and theusual housing with a rubber diaphragm positioned therein on one side ofthe hydraulic chamber, a piston fitting against the other side of thediaphragm and being slidable in a cylinder, the piston being actuatedusuand when fluid is forced into the expansion chamber the diaphragmsare stretched, pressing against the pistons and forcing the sameoutwardly, thus transmitting pressure.

My invention so far as its general and specific applications areconcerned, will be more readily understood from the followingdescription and drawings, in which:

Figure 1 is a longitudinal section through part of a motor vehicleindicating the manner of mounting the compressor and the application ofthe hydraulic power to external type brakes;

Figure 2 is a rear view the compressor as if taken in the direction ofthe arrow 2 of Figure 3;

Figure 3 is a longitudinal section of the compressor taken on the line3-3 01 Figure 2;

Figure 4 is a section of the power applying mechanism, being taken onthe line 4-4 of Figure 5;

Figure 5 is a longitudinal section of the power applying mechanism,being taken on the line 5-5 of Figure 4;

Figure 6 is a perspective view of one of the pistons of the powerapplying mechanism;

Figure 7 is a perspective view of an angular ring for holding thediaphragm in position;

Figure 8 is a perspective view of a clamping sleeve for clamping theangular ring and diaphragm in proper position in the cylinder;

Figure 9 is a perspective view of one or the resilient diaphragms whendismounted in an unrestrained position;

Figure 10 illustrates a modification of the power applying mechanism,having only one piston, being a longitudinal section;

Figure 11 is an elevational detail of the application of the powerapplying mechanism to internal expanding brakes.

The compressor is constructed substantially as follows, having referenceparticularly to Figures 1, 2 and 3:

The frame of the vehicle is designated by the numeral 1 on which ismounted a brake lever or pedal 2 having a foot rest 3. This pedal has anub 4 bearing against the outer end 5 of 'a piston 6. This piston ismounted in a cylinder 7 and has a coiled spring 8 normally bearingagainst the outer end 9 of the cylinder and against a flange 10 of thepiston head.

A pump or compressor casing 11 having a domed side 12 and flanges 13 isconnected to the cylinder by screw threads or the like 14 and clamps adiaphragm designated generally by the numeral 15; This diaphragm has arim 16 and an imperforate web 17, the rim extending preterpistons 40 fitinside ably on both sides of the diaphragm. It is preterable to have arecess 18 formed in the outer periphery of the cylinder and an annulargroove 19 formed in the flange 13 to receive the rim of the diaphragm.The base 20 of the piston bears directly against the diaphragm. Thecasing 11 forms fluid chamber 21 and is provided with a fllling openingwhich is normally closed by a plug 22 and the outlet 23 is connected tosuitable piping such as 24 leading to the power applying mechanism.

The manner of working of my pump or compressor above described issubstantially as follows:

When the foot pedal or any other suitable device is operated 'so as topress on the piston head 5, the base of the piston is forced against thediaphragm and in particular against the web 17 and distorts or stretchesthe web somewhat as illustrated by the dotted lines 25 of Figure 3,thereby compressing the liquid in the liquid chamber 21 and forcing itthrough the various pipes to the power applying mechanism.

In an automobile there would preferably be either two pipes for rearbrakes or four pipes for both front and rear brakes. When the foot pedalis released the spring 8 forces the piston outwardly and allows thediaphragm to be returned to its normal position. The fluid is forcedbackwardly into the fluid chamber by the power applying devices ashereunder set forth or in any suitable manner.

The power applying devices as applied to a double cylinder constructionare substantially as follows, having references particularly to Figures1, 4, 5, 6, 7,8 and 9:

In Figure 1 a wheel is designated generally by the numeral 30 shown ashaving a brake drum 31 with a contracting brake band 32 extending partlythereabout. An axle structure is designated by the numeral33 or theremay be provided any other suitable device to support the cylinder 34,the cylinder 34 in external configuration complying to standardconstruction so that my invention may be applied to standard cars.

The brake band is operated by' fingers 35 mounted on fixed pintles 36having slidable engagements with the stem ends 37 of the brake hand,there being springs 38 to free the band from the drum after the powerhas been released. These fingers press against the heads 39 of thepistons designated generally by the numeral 40.

The cylinder 34 is formed as follows:

A double ended cylinder 41 is provided with barckets 42 and 43 withapertures 44 therethrough to allow attachment to a suitable supportingstructure, this being a standard, and known construction. The cylinderis formed with a central chamber 45 and has annular grooves or recesses46. Angle rings 4'7 having a cylindrical flange 48 and a radial flange49 are fitted into the cylinders and engage the diaphragms 50. Thesediaphragms have a rim section 51 and an imperforate web section 52,these being similar to the rim and web portions 16 and 17 shown inFigure 9.

Clamping sleeves 53 shown ure 8 are threaded into the cylinder 41bearing against the radial flanges 49 of the rings 47. These sleeveshave .iotches 54 to allow insertion of set screws 55 extending throughthe cylinder to retain such sleeves from rotation. The

the sleeves 53 and haveslidbeing restrained by the particularly inFiging motion therein 56 in the inward motion and the bases 57 of thepistons practically touching the webs of the diaphragms. Thesediaphragms when compressed assume an arched shape as shown in Figure 5.

The inlet to the power applying mechanism from the pipes 24 is through acoupling pipe 58 leading to a tubular coupling 59 secured by a bolt 60to the inlet 61 of the cylinder. The fluid passes through the transversepassage 62 and through the passage 63 into the expansion chamber 64which corresponds substantially to the chamber 45. There is preferably aplug 65 to close the passage 62 at the end opposite the inlet.

The manner of operation of the power applying mechanism above describedis substantially as follows:

When the fluid has been compressed in any suitable manner and forcedthrough the pipes 24 into the expansion chamber 64 the diaphragms arestretched so that the webs 47 of the diaphragms press tightly againstthe base of the pistons, forcing such pistons outwardly or apart asshown in Figure 5, the pistons as above mentioned pressing on thefingers 35, thus applying the brake band by applying a tension theretoand drawing it tight around the drum. When the compressor or pump isreleased the fingers, due to the spring action pressing on the pistonsforce the same inwardly and force the fluid from the compression chamber64 back to the fluid chamber 21 of the compressor.

In the construction shown in Figure 10 the power applying device hasonly one diaphragm, there being a cylinder having an annular groove 71therein, a diaphragm 72 having a rim 73 held therein, the imperforateweb 74 stretching across the cylinder. An angle ring 75 similar to theconstruction shown in Figure 7 is held in place against the rim of thediaphragm by a clamping sleeve 76 of a similar construction to thatshown in Figure 8, this sleeve being threaded in the cylinder and heldfrom rotation therein. A piston 77 of a construction similar to thatshown in Figure 6 has a sliding motion in the sleeve and is pressedagainst by a .diaphragm. The inlet 78 receives the fluid undercompression from any suitable source and there is also provided a plug79 to allow refilling if necessary.

My invention may readily be applied to internal expanding brakes asshown in Figure 11 in which a brake drum is indicated by the numeral 80and the brake bands 81 being pivotally connected together by a pivot pin82, this being supported in a suitable manner and having a spring 83 todraw same together. A cylinder 34 may be mounted in amanner somewhatsimilar to thatshown in Figure 1. In this construction it is desirableto provide the pistons with extensions 84 which bear against lugs 85 onthe inside of the brake bands. Therefore when the liquid in theexpansion chamber of the cylinder forces the pistons outwardly, thebrake bands are thrust apart, thereby applying the braking power to thewheels. After the compressor is released the spring 83 releases thebands from the drums, aiding the forcing of the liquid from the powerapplying device back to the compressor. This action is also aided by.the spring 8 forcing the piston 6 outwardly and thereby creating 'avacuum.

Although my hydraulic appliances have been illustrated in connectionwith hydraulic brakes for automobiles or the like, it will be manifestthat the device or construction utilizing a diaphragm to transmitpressure may be utilized in many other applications and provide anabsolutely leak-proof mechanism so far as the compressors are concerned,in which the action is of a limited stroke and to power applyingmechanism which also have a comparatively limited stroke, such strokebeing insufficient to expand or stretch the diaphragm beyond its powerto return.

A characteristic feature of my invention, both as applied to thecompressor and to the brake actuating cylinders, is that the diaphragmhas an integral web and rim, the web being imperforate and of materialhaving the same characteristics throughout. The whole of the diaphragmis of resilient material and the web is flexible, therefore it maystretch and retract into its original position and condition. Therefore,when the piston in the compressor is forced inwardly, it stretches theweb, thereby compresing the fluid in the compressor without any chanceof leakage adjacent the rim or the piston. Also, in the brake actuatingcylinders, the compressed fluid acts on the web of the diaphragm andstretches this so that the fluid exerts a pressure through the stretcheddiaphragm on the pistons and forces these outwardly. This web in thebrake cylinders also retracts due to its resiliency.

Another characteristic of my invention is that the rim portion is ofmuch greater cross-sectional area than the adjacent portions of the web.While'this rim is illustrated as of a cylindrical formation, it isobvious that the shape may be' changed without departing from myinvention. This construction of the rim enables such rim to be clampedin the structure forming the compressor and in the structure forming thebrake operating cylinders in such a manner as to make a leak-proofJoint, which is especially so on account of the resiliency andelasticity of the rim.

Another characteristic of my invention is that in the compressor orpulse-producing device a single piston is utilized, such piston causingthe compression of the fluid acting through the web of the diaphragm.This compressed fluid is conveyed to a fluid chamber of considerablevolume in the brake-actuating or pulse-receiving device which has theflexible web of the diaphragm on one side of such chamber. Therefore,im-

mediately the fluid is compressed in the compressor or pulse-producingdevice the action is communicated to the brake-operating orpulsereceiving device on account of the large volume of fluid heldtherein.

It is obvious therefore that my invention may be considerably modifiedin general construction or in speciflc details to adapt same todifferent installations. Such changes would be within the spirit of myinvention as set forth in the description, drawings, and claims. isHaving described my invention. what I claim 1. In a device as describeda structure having a fluid chamber, a rubber diaphragm having anentirely closed, flexible, stretchable, and retractable web, and acontinuous, integral, somewhat cylindrical rim, means to secure oneportion of the rim to the said structure, an angular ring having aradial flange eng in one edge oftne rim and having a cylindrical flangeengaging another portion of the rim, and means to clamp the ring againstthe said rim, the web forming a closure for one side of the chamber, anda cylinder having a slidable piston positioned to bear against the webon the side opposite the chamber.

2. In a device as described the combination of a structure having afluid chamber and an annular groove in said structure adjacent saidchamber, a rubber diaphragm having a continuous, cylindrical rim, and anintegral imperforate web connected to the. rim, one portion of the rimfltting in the said groove and the web forming a closure tor one side ofthe chamber, an angular ring having a radial flange engaging one end ofthe cylindrical rim and having a cylindrical flange engaging acylindrical portion of the rim,

means to clamp the ring against the said rim toform a fluid-tight seal,and a cylinder structure having a piston bearing on the side of the webopposite the chamber.

3. In a device as described a structure having a fluid chamber with anannular groove adjacent one side of the chamber, a rubber diaphragmhaving a continuous, cylindrical rim with one portion fitting in thesaid groove and having an integral, imperforate web, an angular ringhaving a radial flange engaging one portion of the rim and having acylindrical flange engaging another portion of the rim, a sleeve topress the ring in contact with the rim, and a piston slidable in thesleeve to engage the web on the side opposite the chamber.

4. In a device as described, the combination of a structure having afluid chamber and an annular groove in said structure adjacent saidchamber, a rubber diaphragm having a continuous, cylindrical rim, and anintegral imperforate web connected to the rim, one portion of the rimfitting in said groove and the web forming a closure for one side of thechamber, an annular cylindrical member having a radially directed flangeengaging one end of the cylindrical rim and having an axially directedflange engaging a cylindrical portion of the rim, threaded means toclamp the cylindrical member against the said rim to form a fluid-tightseal, and a piston bearing on the side of the web opposite the chamber.

5. In a device as described, the combination of a cylinder havinga fluidchamber and an annular groove in said cylinder adjacent said chamber, aflexible diaphragmhaving a continuous, cylindrical rim, and an integralimperforate web connected to the rim, one portion of the rim fltting insaid groove and the web forming a closure for one side of the. chamber,means for sealing said rim.

to said cylinder including a cylindrical member having a pair ofangularly related surfaces, one extending in a generally radialdirection and engaging one end of the cylindrical rim, the otherextending in an axial direction and engaging a cylindrical portion ofthe rim, and said means further comprising a sleeve back of said memberand threaded into the cylinder and internally formed as a bearing for apiston engaging said web on the side opposite the chamber.

- JOHN A. DE VITO.

